


who would believe

by keijitrash



Category: Haikyuu!!
Genre: AU, Family, Fluff, Gen, I love this headcanon, Not Beta Read, Sakusa And Matsukawa Are Brothers, Siblings, sakuatsu if you squint
Language: English
Status: Completed
Published: 2020-09-05
Updated: 2020-09-05
Packaged: 2021-03-07 02:40:40
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,076
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/26299555
Author URL: https://archiveofourown.org/users/keijitrash/pseuds/keijitrash
Summary: matsusaku siblings au! where issei and kiyoomi are siblings but no one really believes that - no matter how true it is.
Relationships: Matsukawa Issei & Sakusa Kiyoomi, Miya Atsumu/Sakusa Kiyoomi
Comments: 3
Kudos: 144





	who would believe

**Author's Note:**

> reposted from my [twitter](https://twitter.com/wyannyin)!

No one would believe that one Matsukawa Issei and one Sakusa Kiyoomi are actually siblings. One, there's the concern of having different surnames names and two, they live far away from each other. But if anyone stayed and listened to whenever Issei would sit and talk about 'my brother who's in Tokyo', they would probably believe him afterwards.

As they should.

+++

Issei had originally been from Tokyo. His childhood was filled with towering buildings, red and yellow lights, and a little brother named Kiyoomi.

  
  


("Turns out, they wanted yoomi's name to be something that starts with 'J' but mom switched it to Kiyoomi when she held him the first time.")

  
  


Then their parents separated.

It's the only part of the story that Issei doesn't like talking about - mostly because of the pitying looks he gets from others. Partly because he doesn't like thinking about the time he and Kiyoomi got taken away from each other.

  
  


(His younger brother had gripped his shirt then, told him he didn't want to go anywhere without his "'ssei-nii", but there was nothing he could do.)

  
  


He moved to Miyagi with his mom, and Kiyoomi stayed in Tokyo - a five hour train ride away from Issei's new home.

The only thing that made the separation a little easier for the siblings was the existence of technology. So even when they weren't at literal arm's length from each other, at least they were a phone call away.

  
  


(Their contact names for each other remain, up to this date, as 'Yoomi' and 'ssei-nii'.)

* * *

"We'll get to Nationals, just you wait."

Issei would eagerly say this whenever Inter-High nears. But it's been two years and they still haven't gotten past Shiratorizawa. This time, in his last year in Aoba Johsai, he's hoping for a miracle that maybe they would finally be able to.

  
  


(Then Karasuno entered the fray.)

  
  


"I'll watch you from the stands," Issei tells Kiyoomi when he brings the bad news, "just like always. Sorry we never got to play against each other."

His brother doesn't speak for a moment, but his voice cracks a little when he replies:  _ "It's fine. We have plenty more chances to in the future." _

Issei conveniently tells himself that the voice crack was from the static of his phone, just so his won't do the same. He's the older one here - so he should be the strong one. Emotionally, at least, if not physically. 

"You're right," Issei says, trying to smile even when no one's there to see. "Plenty of chances."

  
  


(He'll have to talk to his brother about what he plans on doing in the future. No matter how much he doesn't want to, Issei knows he  _ should _ . He would disappoint Kiyoomi by not playing volleyball, but it would hurt him more if he figures it out by himself.)

* * *

Fast forwarding to 2018, where Kiyoomi is part of the Black Jackals, and Issei is still searching for a job...

+++

"...are you sure they would let me in?" Issei furrows his brows. Kiyoomi just told him that they could see each other in the court that the Jackals had rented out for the day, and he's not sure he'd be allowed inside. "I don't even play volleyball anymore."

He could already tell that Kiyoomi just rolled his eyes at the question.

"Then tell me when you're here so I can get you."

Issei lets out one big sigh and gives up. "Okay fine. Fine. I'll text you when I get there."

  
  


(But he doesn't. Instead, he walks up to the guards, tells them that he's Sakusa Kiyoomi's older brother, gets scoffed at and told that Sakusa has no siblings. Only  _ then _ does he text Kiyoomi.)

  
  


"I told you we were siblings," Issei scoffs as he walks to Kiyoomi's side. He sneaks a glare at the guards at some point, and his brother turns to him with a 'really?' look. "What? I told them I'm your brother, they didn't believe me. Should I have styled my hair like yours and put two moles on above my right brow?"

Kiyoomi shakes his head, "Please don't."

  
  


When the two of them get in the court, the first thing Issei notices is the enthusiastic redhead who instantly meets his eyes.

"Ah—Number Ten!"

Hinata runs to them, ball in hand, and exclaims: "Scary blocker!"

Kiyoomi looks utterly confused. Does his brother explain what on earth is going on? No, he does not.

"What are you doing here with Omi-san, Matsukawa-san?"

Issei shrugs, "We're siblings."

  
  


Hinata's  **_'what'_ ** might've been able to beat Bokuto's loudest scream if his voice didn't waver mid-word.

* * *

No one would believe that one Sakusa Kiyoomi and one Matsukawa Issei are related. One, because people don't recall ever seeing them together and two, their personalities are very different. But then again, Komori's is also different from Kiyoomi's...

Oh well, they just don't believe it.

But if Kiyoomi just opened up to anyone else but his cousin about what happened to him and his brother, then people would definitely eat up the story and say it's real.

Still, now that they're adults, it's not like they have to hide the fact that they're blood related.

(Not that they did when they were younger, no one just believed Issei when Kiyoomi became a Top Spiker.)

And now, sitting in the benches and watching the three-on-three match of the Jackals, Issei can proudly scream "Go little bro!", even if it would embarrass the said 'bro'.

  
  
  


Something worth mentioning:

Just because they've been separated from each other doesn't mean that Issei can't tell what his brother is thinking.

So when he sees Kiyoomi hide a smile when Number 13 compliments his spike, Issei's brows shoot up and a grin spreads across his face.

He approaches Number 13 when he's switched out, puts a hand around his shoulders, then asks: "Miya, right? What do you think of my brother?"

The blond's face practically bursts into flames at the question - either because he's not used to the causal touchint, or because he'd just ask the poor setter about Kiyoomi. Issei guesses it's the latter.

The brunet leans close to the setter's ear.

"What if I told you," he pauses for effect, "that Kiyoomi might have an itty-bitty-teeny-tiny crush on you?"

  
  


(One can only imagine how chaotic the rest of it goes.)

(Spoiler alert: it ends with Issei messaging his group chat with Oikawa, Iwaizumi, and Hanamaki with the words 'Guess who's a matchmaker now?'.)

**Author's Note:**

> I'd love to hear your comments and reviews below!! ❤ I hope you enjoyed this oneshot :>
> 
> Check me out on [twitter](https://twitter.com/wyannyin) where I'm more active in writing twtfics


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